NEW YORK — Amazon, which began shipping a tablet computer this week, may be eyeing the smartphone market. Citigroup said in a research note published on Thursday that it believes the Seattle-based online retail giant plans to launch a smartphone...

With nearly 30 million iPads sold, Apple is the undisputed tablet computer champion. BlackBerry maker Research In Motion, US computer giant Hewlett-Packard, South Korea’s Samsung and scores of other companies with devices powered by...